Hydraulic brake:
The hydraulic brake system used in automobile is a multiple piston system. A multiple piston system allows forces to be transmitted to 2 or more pistons. hydraulic brakes is a brake system in which the brake pedal moves the piston in the master cylinder and the brake fluid then applies great force to the brake pads.
The master brake cylinder converts force exerted on the brake pedal into hydraulic pressure to apply the brakes. Depressing brake pedal moves the push rod in the master cylinder. Pair of pistons are mounted on the push rod 1 after the other to push against the fluid inside the master cylinder bore. This creates pressure which displaces fluid as brake fluid is incompressible. As brake fluid is pushed from the master cylinder, it exerts pressure through brake lines to apply each of the brakes.
When the brake pedal is released, spring-loaded piston assembly in master cylinder returns to its rest position. The fluid which was displaced by the pistons is pushed back to the master cylinder as the disc brake pads kick out away from rotors, and the springs inside the drums retract the brake shoes. The fluid returns to the brake fluid reservoir by the compensating ports, which are small openings among the master cylinder bore and fluid reservoir just ahead of each of the pistons. Master cylinders are divided into 2 separate hydraulic circuits, with each of it having its own fluid reservoir and piston. With most rear-wheel-drive vehicles, hydraulic system can be divided front to rear with one circuit for the front brakes and a second circuit for the rear brakes. On the several front-wheel- drive cars, brake system is split diagonally. The left front and right rear brakes share 1 circuit, while the right front and left rear brakes share the other. To reduce hydraulic pressure to the rear brakes so the rear brakes don't lock up when the brakes are applied, a proportioning valve is required. This valve compensates differences in the weight distribution front-to-rear in addition to the forward weight shift which occurs when the brakes are applied.